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Why can cross-modal plasticity affect the success of retinal implants or cochlear implants?

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neuroplasticity The fundamental cell of the nervous system is the neuron. Neurons in a human brain are shown here.

Cross-modal plasticity can significantly impact the success of retinal implants or cochlear implants because it involves the functional reorganization of the brain in response to sensory deprivation.1

When an individual experiences long-term vision or hearing loss, the brain does not remain static. Instead, the cortical areas typically dedicated to processing those specific senses—such as the visual or auditory cortex—may be "commandeered" by other sensory modalities, such as touch or vision, to compensate for the deficit.21

Because these brain regions have been repurposed to process different types of information, they may no longer be available or effectively structured to interpret the signals provided by an implant. Consequently, if the visual or auditory cortex has been extensively reorganized to serve other functions, the implant may prove ineffective, as the brain is no longer "tuned" to receive or process the original sensory input. The extent of this reorganization, which varies based on factors like age and the duration of sensory deprivation, is a critical determinant in the clinical success of these rehabilitative technologies.1